Head flow testing.

comnoz

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Fullauto said:
Does'nt a bent valve give better flow? Something about airflow around a curve rather than in a straight line? I dunno. You're the expert!

Oh yeah, it flows great, open or closed....
 

Fast Eddie

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comnoz said:
Fast Eddies RH10 head before and after a street port job with 3mm oversized intake valves.

Fast20Eddies20Head_zpsvucq6qdl.jpg

I thought I'd post this update in Jims thread to make it easier for folk searching this topic.

More info on this topic fine build can be found here:
engine-build-prep-t18461-165.html?hilit=Cylinder%20head%20testing%20Dyno

Jim's graph is based on the following 'before and after' specs:

'Before' spec of bike was: JS1 cam/ follower/ spring kit, JS rods and pistons at 10.5:1 CR, nice squish (forget exact measurment), 35mm FCRs, cNw manaiflod, Tri spark, cNw coils and leads. Standard RH10 head and valves.

'After' spec is: as above plus, followers ground to 7/8th radius instead of 1 1/8, 3mm OS re-angled inlet valves, 1.5mm OS exhaust valves, Comnoz port job, Comnoz valve springs.

Actual peak figure was 64.6bhp @ 6300 rpm, with a very flat power graph from 6000 to 7000. This was a 9bhp (yes NINE BRAKE HORSE POWER, on the same dyno) improvement!

There was significantly more power everywhere from 3000 upwards.

I was very surprised by this to be frank, the improvement way exceeded my expectations.

The summary is that the RH10 head, reworked by Comnoz, gives an outstanding performance improvement. The BHP per $ ratio being far more favourable than most (any?) other mods that I can think of!

Sending your RH10 head to Comnoz should be a compulsory requirement of ownership...!
 

SteveA

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Fast Eddie said:
........Sending your RH10 head to Comnoz should be a compulsory requirement of ownership...!


First find an RH10 head that hasn't already be used and abused!

Not so easy anymore....
 
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You have got about 5 airflow graphs for cylinder head porting on this page. Have you got corresponding dyno curves showing horsepower and torque when you use the head on a standardised configuration bike ?
 

comnoz

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Have you got corresponding dyno curves showing horsepower and torque when you use the head on a standardised configuration bike ?

That would be pointless. To make a performance engine it must be developed as a package. Jim
 
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Gday All,
this is a very intersesting thread, keep it up!
Just wondering has anyone tried an inlet port insert to build up the port floor! Perhaps this could be made from pressed stainless and held in place via the manfold bolts and a devcon type product to hold in situ along the port floor?? :?:

Foxy
I use JBweld on a roughened floor in BSA A65 ports. Never had a problem. Only inlets naturally.
 

cliffa

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This stuff can withstand high temperatures ( I can vouch for that )


They even make one which you could use in the exhaust ports. (Thermosteel up to 2400ºf )
 
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Well here are flow results from Ken's Maney stage 3 head. Big flow numbers for sure. Huge ports and 1.690 inch valves for big inch high RPM use only. The red line is the Maney head . Green is a standard Fullauto and blue is a RH4 that has been flowed by persons unknown. I went all the way to .500 lift although few cams lift beyond .420 or so. Jim

View attachment 35281

Here are the velocity numbers. They are what matters if you want a wide powerband.

View attachment 35282
That's fantastic to see. I've been trying to figure out why a ported head on a stock A65 650 makes so much difference both in response and top end. The response is really nice and instant. I have vacuum cleaners and measurements based on a std BSA port being 109cfm and basing calculations on it. The numbers are just what it gives and probably optimistic, but the relationship is indicated. The red and the green line are through a 34mm PWK. I have stuff to make something to measure port velocity which I can compare when I get time.

The head with the green line works far better than expected on a std engine which I plan dyno testing because of curiosity. It also works on a long stroke 745, not dynoed but 8 wins from 10 starts a 2nd and a dnf, and Queensland P3 sidecar champions.

Please ignore the numbers as it's embarrassing if they are over optimistic. My bench is just a measure that works but of dubious accuracy.
The green line uses a 42mm valve the redline a 44.5mm valve and though it flows more through the 34mm carb I have no idea how it might work. Air has to go faster through the carb but after that in the bigger port I don't know. It's for an 80X74 90 degree, but it needs grunt as well as rpm.



If you look where the gasket is that's the shape as it enters the head. With the big valve the entry is the same but it gets bigger for the valve.

 
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So now that I identified a problem with my prior velocity readings and corrected them -here is the flow tests with the 1.5mm oversize intake and a little work in the valve guide and bowl area.

Nice improvement for a steetbike running a .400 lift cam.

Flow
View attachment 35405

Velocity
View attachment 35406
I've been using a manometer with plastic hose in the port to get an idea of velocity. Hope I am doing it right. Vizard has a chart reading up to 38"w which equals around 400fps. That approximates speed if the bench is testing at 28"w... in theory. Depending where I put the hose end I can get 34" 380fps just in the manifold, 40" 420fps in the port and down near the guide 52" probably 450fps? But that's beyond his graph. It varies depending where it is, it seems fast on the short turn, not that I can see it so well and the hose in there probably affects it.

The port flows well cfm wise, and reducing the bench test pressure to half (14") still has 30" or 360fps in the port. What I don't know is what the engine will pull and what speed may be like on a running engine. This is on a BSA A65 head with 34mm port and 44.5 valve. I also have the same thing with 42mm valve that works well on an engine which I should compare and then a stock port and maybe try mapping as you have above. This is that 34mm manifold transitioning to oval entering the head. It's about 70% more flow than stock 30mm at stock full lift.


This is using a port shape based on the XR750 oval port. As Jim at JSmotorsport talks about often. These threads are extremely interesting and your work. I hope me commenting isn't too annoying. This is an old head with lots of patching in it. Except for the floor it wouldn't need patching but not all cast in seats line up to take 44.5mm valves. Because I was patching this I moved the port down a little and lined it up better.
 
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